Visit Metro Vancouver Levels site here and read the "River Flow m3/s"(CMS) (GREEN line) from the Capilano River gauge.
Use the chart below to roughly covert the CMS to the level indicated at the fish hatchery.
2; 20 cms
3; 30 cms
4; 50 cms
5; 70 cms
6; 90 cms
7; 115 cms
8; 140 cms
*9; 160 cms
*10; 200 cms
* these levels are over the weir and are approximations, be aware that a powerful and unavoidable recirculating hydraulic forms around these levels (video here https://vimeo.com/151471317)
Visit Metro Vancouver Levels site here and read the "River Level" (BLUE line) from the Seymour River gauge.
Use the graph below to roughly covert the gauge level to the level indicated on the rock.
You can view the rock on the river from the end of "Heritage Park Ln, North Vancouver"